bnst lesions aggravate behavioral despair but do not impair navigational learning in rats
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BNST lesions aggravate behavioral despair but do not impair navigational learning in rats. Pezük, Göz, Aksoy, Canbeyli Brain Research Bulletin -2006. Episode I: The Phantom Nucleus. - PowerPoint PPT PresentationTRANSCRIPT
BNST lesions aggravate behavioral despair but do not impair navigational learning in rats
Pezük, Göz, Aksoy, Canbeyli Brain Research Bulletin-2006
Episode I: The Phantom Nucleus
Lesions in the BNST disrupt corticosterone (B) and freezing responses elicited by a contextual but not by a specific cue-conditioned fear stimulus G. M. Sullivan et al
Neuroscience 2004
Sullivan 2004-Intro
Relay station between CeA and PVN Control of HPA response to conditioned
fear stimulus in context Behavioral and neuroendocrine
Cue: simple sensory stimulus (tone) Context: complex environmental
representation (no tone)
Sullivan 2004-Experiment
Day 0 Habituation
Day 1: training Cue: tone (CS) paired with footshock
(US) in home cage Contextual: rats placed in experimental
cage, footshock (US) applied w/out specific cue (CS)
Sullivan 2004-Experiment
Day 3: surgery Lesion CeA or BNST (sham)
Day 8: cue vs. context testing Place rats in experimental cage,
measure freezing (camera) or corticosterone (decapitation/collection of trunk blood)
Sullivan 2004
Figure 1
Sullivan 2004-Results
In CeA, bilateral lesions after training block expression of freezing and cort responses to cue and context
In BNST, lesions only block freezing and cort responses to context No role in freeze/cort responses to tone
Sullivan 2004 (Figure 4)
Sullivan 2004 Conclusions
BNST critical link between CeA and PVN
BNST involved only in regulation of HPA axis responses to unconditioned fear/anxiety (contextual)
Episode II: Attack of the Amygdala
Double Dissociation between the Involvement of the Bed Nucleus of the Stria Terminalis and the Central Nucleus of the Amygdala in Startle Increases Produced by Conditioned versus Unconditioned Fear David Walker, Michael Davis
The Journal of Neuroscience 1997
Walker, Davis 1997-Intro
Compare startle response to light (light-enhanced) or previously paired shock (fear-potentiated)
Examine basolateral Amygdala (blA), central Amygdala (CeA), and BNST
Use AMPA-R antagonist (NBQX) or PBS
Walker, Davis 1997-Previous Findings
BLA lesionsdisrupt conditioned fear responses
CeA lesionsdisrupt individual fear behaviors
BNST lesions disrupt unconditioned fear
BNST and CeA receive inputs from BLA BLAconditioned and unconditioned fear
Walker, Davis 1997-Experiment
Test blA, CeA, and BNST in fear-potentiated startle (cond.) and light-enhanced startle (uncond.)
Intracranial infusions of AMPA-R antagonist (NBQX) into blA, CeA, BNST
Walker, Davis 1997 (Figure 5)
Cannula tip placements in BNST
Walker, Davis 1997-Results
NBQX in BLAdisrupt both behaviors
NBQX in CeAonly blocked fear-potentiated startle
NBQX in BNSTonly blocked light-enhanced startle
Walker, Davis 1997-BLA (Fig 2)
Light-enhanced startle
Mean startle amplitude
Startle amp increase in bright light vs dark
Walker, Davis 1997-BLA (Fig 3)
Fear-potentiated startle
Startle amp increases with combination of light CS and startle stimuli
Walker, Davis 1997-CeA (Fig 4)
No significant effect of NBQX on light-enhanced response in CeA
Startle amp greater with combination of light CS and startle stimulus than startle stimulus alone
Walker, Davis 1997-BNST (Fig 6)
Illumination enhances startle
NBQX disrupts phase 1 to phase 2 increase in startle amp
NBQX infusions in BNST block light-enhanced startle independently
Walker, Davis 1997-BNST (Fig 6C)
No effect seen with NBQX on fear-potentiated startle
~startle amp increased w/light
Walker, Davis 1997 Conclusions
BLAsensory center in light-enhanced startle response
CeAcontrol center of fear-potentiated startle
BNSTrole in light-enhanced startle response
Double dissociation between BNST and CeA in response to light-enhanced and fear-potentiated startle
Episode III: Revenge of the BNST
BNST lesions aggravate behavioral despair but do not impair navigational learning in rats Pezük, Göz, Aksoy, Canbeyli
Brain Research Bulletin-2006
Introduction
BNST lesions can aggravate behavioral despair Effects of behavioral despair on cognitive
function unknown BNST involved in autonomic,
neuroendocrine, and motivational responses to stress
BNST modulates HPA axis response to stress Effects on memory and learning
Hypothesis
Animals with BNST lesions will show impaired performance in navigational learning tasks (Morris Water Maze)
Impaired acquisition of navigational learning in BNST-lesioned animals
Materials/Methods
Male Wistar rats (260-275g) 12/12h light/dark cycle (lights on @ 0700) Stereotaxic surgery (electrolytic lesions) 14 BNST-lesioned and 8 sham 2 weeks post-surgeryFST 1 week after 2nd FSTMWM 2 weeks after MWMopen field (OF) test
Location (Figure 1, anterior)
Location (Figure 1, posterior)
Results-Forced Swim Test
*
Increased immobility in BNST-lesioned animals
Figure 2
Results-Morris Water Maze
No difference seen between experimental groups
Figure 3
Results-Open Field Test
Apparatus with 64 squares on floor Explore for 5 minutes Measure locomotor activity No significant difference seen
between experimental groups
Discussion
BNST lesions cause longer periods of immobility in Forced Swim Test
BNST lesions have no effect on navigational learning (MWM)
BNST-role in depression BNST-learning during stressful
situations
Conclusion
BNST-dissociation between depressive behavior and spatial learning BNST involved in behavioral despair
(depression), but not spatial learning